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coastie124

I'm thinking about buying a 924s project car but it doesn't have a fuel pump. I have a 924 fuel pump available. The 924s operates at 58psi 38gpm and the 924 operates at 73psi 56gpm. Would I be able to use the 924 pump?

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Should be, the fuel pressure regulator will just return the excess fuel to the tank.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

. . .except I understood the 924 CIS pump to run at quite a bit higher pressure than that. Perhaps I am mistaken.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Shouldn't matter, the regulator will hold the pressure at the proper level.

People convert CIS cars to EFI quite often and use off the shelf regulators to regulate the stock CIS fuel pumps to 50-70psi base fuel pressure.

Its like your water faucet. Street pressure is 16psi (I think) but you don't necessarily get 16psi worth when you crack the tap, right?

Many multi-point EFI pumps (even CIS) are capable of 150+psi out of the box, doesn't mean that is what you'll get all of that at the rail unless your regulator is set to do so (or if your return line is too small)

People swap in higher flowing pumps all the time in their EFI cars and then complain that their cars don't go any faster. That's because they're still using the same amount of fuel pressure as they were before. Adjust the injector sizing, injector timing or the base fuel pressure and you'll notice a change in how the engine runs (unless the old pump was shot).
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

masterdave · Joined: 10 Dec 2008 Posts: 183 Location: Harrison NY

you should be fine, it may draw a bit more power but the return fuel line will just dump the extra fuel back in the tank, you may notice that the engine is running a bit rich when you slam on the gas, the computer knows how long to open the injectors for, when they are running at stock pressure the increase in pressure may cause a bit more gas to get through, but i dont see it being an issue.